Enalapril, atenolol, and hydrochlorothiazide in mild to moderate hypertension. A comparative multicentre study in general practice in Norway.

Enalapril, atenolol, and hydrochlorothiazide were compared in a double-blind randomised parallel study in general practice. 436 patients with mild to moderate hypertension were included at 76 centres. A two-week placebo run-in period was followed by 16 weeks of monotherapy. The initial doses were: enalapril 20 mg; atenolol 50 mg; and hydrochlorothiazide 25 mg. These were doubled if treatment was not effective after 4 weeks. Adverse reactions were the main reason for withdrawal from the study (9 on enalapril, 19 on atenolol, and 8 on hydrochlorothiazide). Systolic and diastolic blood pressures were significantly reduced in all three groups. The reduction in systolic blood pressure was greater on enalapril than on atenolol. Serum potassium was reduced and uric acid increased on hydrochlorothiazide. Fasting blood sugar rose on atenolol but fell on enalapril. The frequency of adverse reactions was acceptable in all three groups. After 16 weeks on treatment significantly more adverse reactions were recorded in the atenolol group than in the enalapril group. Enalapril is effective and well tolerated in patients with mild to moderate hypertension.